The history of Groupe M
The history of Groupe M: building, passing on, innovating
The Groupe M story began in 1999 with the creation of the founding company MONTEIRO, established by Éric Monteiro, a recognised nuclear expert. Driven by a passion for piping, boilermaking and high-technology welding, he laid the foundations of demanding industrial know-how. It was in this context that his son, Julien Monteiro, took his first steps as a welder, developing in the field a detailed understanding of industrial trades through a largely self-taught career.
A few years later, Annabel Vigier and Julien Monteiro took over the company together and made it the cornerstone of Groupe M. As partner-directors, they combined their experience and vision to structure, diversify and grow the Group, turning it into a leading industrial player recognised in France and internationally.
Their complementary strengths – managerial rigour, hands-on field experience and a shared ambition – have transformed a family-owned SME into a leading group in its areas of expertise.Today, Groupe M puts its know-how at the service of the low-carbon energy, defence, shipbuilding, research and process industries sectors.
More than an industrial group, Groupe M is the result of a human adventure built on the passing on of skills, passion and a vision for the future.
Creation of Groupe M with its founding company Monteiro. Development of piping and welding activities in the nuclear sector.
New Monteiro branches opened in Briare (45) & Pierrelatte (26).
Growth in the activities of the Industry and Fuel Cycle unit.
Creation of the Energy & Industry division at Monteiro.
Monteiro establishes a presence at the Orano Malvési site.
Monteiro establishes a presence at CEA Cadarache.
New Monteiro branch opened in Bagnols-sur-Cèze (30).
Acquisition of CHAUSSY, a company specialising in industrial machining based in Donzère (26).
External growth through the acquisition of the boilermaking division of ONET Technologies (Monteiro).
Acquisition of CTI, a company based in Agneaux (50) specialising in the custom manufacture of boilermaking and welded mechanical equipment.
NOVA is founded in St Fons (69). It comprises 2 areas of expertise: integrated engineering consultancy and inspection/NDT.
New Monteiro branch opened in Sasseville (76).
New Monteiro branch opened in Vinon-Sur- Verdon (83).
2 new Monteiro branches opened in St-Aubin-de-Blaye (33) & St-Pierre-des-Corps (37).
Integration of IRI into CHAUSSY GOMEZ. IRI is based in Bobigny (93) and specialises in valves.
Acquisition of the companies SECOMOC, ECCR and MATEN METROLOGIE, leaders in tank construction and maintenance.
Groupe M wins the gold medal at the 2023 French Welding Championship – 3-Process Course
New Monteiro branch opened in Montrouge (92) and extension of our Monteiro branch in Briare (45).
New branch opened in Téteghem (59) (SECOMOC & MONTEIRO).
Winner of the Auvergne-Rhône-Alpes region's reshoring trophy for the construction of our new headquarters and new plant in Saint-Paul-Trois-Châteaux (26).
Move to our new headquarters in Saint-Paul-Trois-Châteaux (26).
Julien MONTEIRO receives the Entrepreneur of the Year award for Auvergne-Rhône-Alpes.
3 years of Groupe M commitment alongside EDF for the CSC (Chaussy Gomez, Nova, Monteiro)
Groupe M, partner of the 2025 French Welding Championship, hosts the regional qualifiers at its plant in Saint-Paul-Trois-Châteaux (26).
TotalEnergies Contractor Recognition Award – ICC GREEN RATING received by Secomoc and ECCR.
Strategic industrial partnership with Fabtech Group in the United Arab Emirates.
Monteiro wins the Readers' Choice award from L’Echo Drôme Ardèche – L’industrie fait son cinéma.
Creation of the Facility Management division and the Prose FM entity within Groupe M.
Acquisition of DB Power and integration into the Reactors division.
Groupe M wins 2 medals at the 2025 French Welding Championship.
Groupe M acquires a stake in Hexana.
Groupe M strengthens the offering of its Mechanical & Valves division, led by Chaussy, with the acquisition of Mécavibre in Pierrelatte (26).
Acquisition of Altitude TS in Malataverne (26). The company joins the Facility Management division of Groupe M.
Groupe M receives the Entrepreneurs' Yellow Jersey awarded by LCL as part of the 2025 Tour de France.
Groupe M welcomes Tibo in Shape for the opening of the gym at its headquarters in Saint-Paul-Trois-Châteaux.
Acquisition of the company Alliages Groupe and its integration into the Reactors, Mechanical & Valves and Facility Management divisions of Groupe M.
Acquisition of the company EFINOR and its integration into the Industry & Process and Mechanical & Valves divisions of Groupe M.
A new visual identity for Groupe M, with new logos for each of its entities.
Groupe M at the Fabriqué en France exhibition at the Élysée Palace, showcasing our unique know-how: XXL boilermaking, 100 % Made in France, serving the nuclear industry.
Groupe M wins the Women Energy AWARD 2025 !
Nova awarded a medal at the Fem'Energia 2025 awards : a source of pride for Groupe M !
Groupe M expands its Facility Management scope with Prose LOG and Prose DEM !
Groupe M receives the 2025 Company of the Year award at the Franco-Portuguese Chamber of Commerce and Industry Gala.
Alain BUNEL appointed Managing Director of Monteiro and Vice-President of Efinor Allais, Efinor Sea Cleaner, Efinor Metal, Efinor Engineering ELEC, Efinor Interventions and DB POWER.
Acquisition of the British company Lakers, specialising in piping, welding and mechanical solutions projects, within Groupe M.
Julien MONTEIRO joins the Choiseul 100 2026 ! The ranking recognises 100 young leaders under 40 who are actively helping to transform the French economy.
Integration of DPI into Monteiro.
A new SECOMOC location in Douala, Cameroon.
Looking to develop your career in a dynamic environment that places innovation and industrial excellence at the heart of its priorities? At Groupe M, we value talent and offer rewarding career opportunities.